Effect of small vanadium addition on the microstructure, transformation temperatures, and corrosion behavior of a Cu72Al17Mn11 shape memory alloy
Ricardo Francisco Alves, Rafael A. Raimundo, Bruno Alessandro Silva Guedes de Lima, Danniel Ferreira de Oliveira, Renato Alexandre Costa de Santana, Rodinei Medeiros Gomes, Carlos José de Araújo
Abstract
In the present work, effects of 0.1 at.% and 0.2 at.% vanadium content on the microstructure, transformation characteristics and corrosion behavior of the Cu72Al17Mn11 shape memory alloy (SMA) have been investigated by means of OM, SEM, XRD, DSC measurements and corrosion test. The alloys were produced in an induction furnace under air atmosphere. The results indicate that microstructure at room temperature consisted of a mixture of β3(L21) parent phase with 0.06–0.08 at% of vanadium into solid solution, small amounts of a cubic bcc δ(V,Mn) precipitate, β1′(18R) and γ1′(2H) martensites. The small addition of vanadium contributes to the induction of martensite γ1′ and broads the hysteresis of the alloys. Thermal analysis evidences the shift of Af, Ms to higher temperatures, showing multi-stage phase transformations of the reaction β1′→γ1′→β3, which results in increased values of ΔHM→A, ΔSM→A, ΔGe. The addition of V also interfered in the corrosion resistance of the alloy. Electrochemical measurements were carried out to evaluate the corrosion resistance alloys. With the results obtained, an increase in corrosion resistance was observed with the increase in the vanadium content in the alloy. The results of this work provide an important systematic analysis for the development and application of corrosion resistant CuAlMn SMA.